Broadcast communication system with dynamic client-group memberships

Abstract

In an embodiment, a communication system may include a system host that transmits messages to a number of client devices, which may be dynamically grouped. The system host may link the client identifier of a client in a group to a group identifier and an expiration indicator in a client-group database. The membership information in the database may be updated as groups are added, deleted, or modified, or as client memberships expire. The system host may compile a general membership file from information in the client-group database and transmit it at scheduled intervals. Client devices may update their membership files with the transmitted file and by deleting expired membership records. The system host may transmit messages that include a group identifier in a header. A client device may inspect the header and discard the message if the transmitted group identifier is not found in that client device's internal membership file.

What is claimed is:  
     
         1 . A method comprising: 
 storing membership data at a client having a client identification, said membership data including a first group identifier corresponding to a first group and a first expiration indicator;    transmitting a group membership file at a host, said group membership file including a second group identifier associated with a member identifier and a second expiration indicator; and    updating the membership data at the client.    
     
     
         2 . The method of  claim 1 , wherein updating the membership data comprises: 
 examining the first expiration indicator to determine if membership in the first group has expired; and    deleting the first expiration indicator and the first group identifier in response to a determination that membership in the first group has expired.    
     
     
         3 . The method of  claim 1 , wherein updating the membership data comprises: 
 receiving the group membership file at the client;    comparing the member identifier to the client identification; and    storing the second group identifier and the second expiration indicator at the client in response to the member identifier matching the client identification.    
     
     
         4 . The method of  claim 1 , wherein the group membership file includes the first group identifier and two or more member identifiers associated with the first group identifier, and wherein updating the membership data comprises: 
 comparing each of said member identifiers to the client identification; and    deleting the first group identifier and the first expiration indicator in response to the client identification matching one of said member identifiers.    
     
     
         5 . The method of  claim 1 , wherein the expiration indicator comprises a date.  
     
     
         6 . The method of  claim 1 , wherein the expiration indicator comprises a time.  
     
     
         7 . The method of  claim 1 , further comprising: 
 transmitting a message including a payload and a transmitted group identifier;    receiving the message at the client; and    extracting the payload from the message in response to the first group identifier matching the transmitted group identifier.    
     
     
         8 . An article comprising: 
 a machine-readable medium which stores machine-executable instructions, the instructions causing a machine having a client identification to: 
 store membership data, said membership data including a first group identifier corresponding to a first group and a first expiration indicator;  
 receive a group membership file from a host, said group membership file including a second group identifier associated with a member identifier and a second expiration indicator; and  
 update the membership data.  
   
     
     
         9 . The article of  claim 8 , wherein the instructions causing the machine to update the membership data include instructions causing the machine to: 
 examine the first expiration indicator to determine if membership in the first group has expired; and    delete the first expiration indicator and the first group identifier in response to a determination that membership in the first group has expired.    
     
     
         10 . The article of  claim 8 , wherein the instructions causing the machine to update the membership data include instructions causing the machine to: 
 compare the member identifier to the client identification; and    store the second group identifier and the second expiration indicator at the client in response to the member identifier matching the client identification.    
     
     
         11 . The article of  claim 8 , wherein the group membership file includes the first group identifier and two or more member identifiers associated with the first group identifier, 
 and wherein the instructions causing the machine to update the membership data include instructions causing the machine to: 
 compare each of said member identifiers to the client identification; and  
 delete the first group identifier and the first expiration indicator in response to the client identification not matching one of said member identifiers.  
   
     
     
         12 . The article of  claim 8 , wherein the expiration indicator comprises a date.  
     
     
         13 . The article of  claim 8 , wherein the expiration indicator comprises a time.  
     
     
         14 . The article of  claim 8 , further comprising instructions causing the machine to: 
 receive a message including a payload and a transmitted group identifier; and    extract the payload from the message in response to the first group identifier matching the transmitted group identifier.    
     
     
         15 . An apparatus comprising: 
 a receiver to receive messages and a group membership file including a plurality of membership records, a membership record including a member identifier associated with a first group identifier and a first expiration indicator;    a memory to store an apparatus identification;    a membership file to store a second group identifier and an associated second expiration indicator;    a clock to output a current time; and    receiver controller coupled to the receiver, the memory, the membership file, and the clock, said receiver controller operative to update the membership file in response to one of the group membership file and the current time.    
     
     
         16 . The apparatus of  claim 15 , wherein the receiver is operative to compare the client identification to the member identifier in the membership record and to store the first group identifier and the first expiration identifier in the membership file in response to the member identifier matching the apparatus identification.  
     
     
         17 . The apparatus of  claim 15 , wherein the receiver controller is operative to compare the second expiration indicator to the current time and to delete the second group identifier and the second expiration indicator in response to the second expiration indicator exceeding or matching the current time.  
     
     
         18 . The apparatus of  claim 15 , wherein a message includes a transmitted group identifier and a payload, and wherein the receiver controller is operative to extract the payload in response to the transmitted group identifier matching the second group identifier.  
     
     
         19 . A system host comprising: 
 a memory to store a group membership file including data indicative of group memberships;    a group generator to generate membership records in a group membership file, a membership record including a group identifier, a member identifier, and an expiration indicator; and    a group controller to update the group membership file.    
     
     
         20 . The system host of  claim 19 , further comprising a clock to output a current time, and wherein the group controller is operative to compare the expiration indicator to the current time and to delete the membership record in response to the expiration indicator exceeding or matching the current time.  
     
     
         21 . The system host of  claim 19 , wherein the expiration indicator comprises a date.  
     
     
         22 . The system host of  claim 19 , wherein the expiration indicator comprises a time.  
     
     
         23 . A system comprising: 
 a system host comprising: 
 a group generator to generate membership records in a group membership file, a membership record including a first group identifier, a membership identifier, and a first expiration indicator; and  
 a transmitter to transmit the group membership file; and  
 a client comprising: 
 a receiver to receive messages and the group membership file;  
 a memory to store an apparatus identification;  
 a membership file to store a second group identifier and an associated second expiration indicator;  
 a clock to output a current time; and  
 a receiver controller coupled to the receiver, the memory, the membership file, and the clock, said receiver controller operative to update the membership file in response to one of the group membership file and the current time.  
 
   
     
     
         24 . The system of  claim 23 , wherein the second expiration indicator comprises a time.  
     
     
         25 . The system of  claim 24 , wherein the receiver controller is operative to compare the second expiration indicator to the current time and to delete the second group identifier and the second expiration indicator in response to the second expiration indicator exceeding or matching the current time.